powerpc/44x: Support 16K/64K base page sizes on 44x

This adds support for 16k and 64k page sizes on PowerPC 44x processors.

The PGDIR table is much smaller than a page when using 16k or 64k
pages (512 and 32 bytes respectively) so we allocate the PGDIR with
kzalloc() instead of __get_free_pages().

One PTE table covers rather a large memory area when using 16k or 64k
pages (32MB or 512MB respectively), so we can easily put FIXMAP and
PKMAP in the area covered by one PTE table.

Signed-off-by: Yuri Tikhonov <yur@emcraft.com>
Signed-off-by: Vladimir Panfilov <pvr@emcraft.com>
Signed-off-by: Ilya Yanok <yanok@emcraft.com>
Acked-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 14 insertions, 9 deletions

diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 8cba46fc9e3b..38ff35f2142a 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -68,24 +68,29 @@ extern unsigned long p_mapped_by_tlbcam(unsigned long pa);
 #define p_mapped_by_tlbcam(x)   (0UL)
 #endif /* HAVE_TLBCAM */
 
-#ifdef CONFIG_PTE_64BIT
-/* Some processors use an 8kB pgdir because they have 8-byte Linux PTEs. */
-#define PGDIR_ORDER     1
-#else
-#define PGDIR_ORDER     0
-#endif
+#define PGDIR_ORDER     (32 + PGD_T_LOG2 - PGDIR_SHIFT)
 
 pgd_t *pgd_alloc(struct mm_struct *mm)
 {
         pgd_t *ret;
 
-        ret = (pgd_t *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, PGDIR_ORDER);
+        /* pgdir take page or two with 4K pages and a page fraction otherwise */
+#ifndef CONFIG_PPC_4K_PAGES
+        ret = (pgd_t *)kzalloc(1 << PGDIR_ORDER, GFP_KERNEL);
+#else
+        ret = (pgd_t *)__get_free_pages(GFP_KERNEL|__GFP_ZERO,
+                        PGDIR_ORDER - PAGE_SHIFT);
+#endif
         return ret;
 }
 
 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 {
-        free_pages((unsigned long)pgd, PGDIR_ORDER);
+#ifndef CONFIG_PPC_4K_PAGES
+        kfree((void *)pgd);
+#else
+        free_pages((unsigned long)pgd, PGDIR_ORDER - PAGE_SHIFT);
+#endif
 }
 
 __init_refok pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
@@ -385,7 +390,7 @@ void kernel_map_pages(struct page *page, int numpages, int enable)
 #endif /* CONFIG_DEBUG_PAGEALLOC */
 
 static int fixmaps;
-unsigned long FIXADDR_TOP = 0xfffff000;
+unsigned long FIXADDR_TOP = (-PAGE_SIZE);
 EXPORT_SYMBOL(FIXADDR_TOP);
 
 void __set_fixmap (enum fixed_addresses idx, phys_addr_t phys, pgprot_t flags)